Keratoacanthoma is a low-grade malignant tumor, rapidly evolving, that originates in the pilosebaceous glands. The disease is spread across the surface of the globe but with large geographical variations; it is more frequently in males (male / female = 2:1) and Caucasians, with an increased incidence in those over 50 years and prolonged sun exposure.
Clinically, it presents as an exophytic nodule, painless, with a central crateriform ulceration or keratin plug; the tumor margins have many teleangiectatic areas.
Histologicaly examination revealed a crateriform tumor with mases of keratin that constitute the central core of keratoacanthoma. The tumor is composed of squamous epithelium with mild degree of pleomorphism; on top, peritumoral epidermis looks spur or eave.